Correct way to convert size in bytes to KB, MB, GB in JavaScript

Question

From this: (source)

Unminified and ES6’ed: (by the community)

function formatBytes(bytes, decimals = 2) {
    if (!+bytes) return '0 Bytes'

    const k = 1024
    const dm = decimals < 0 ? 0 : decimals
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']

    const i = Math.floor(Math.log(bytes) / Math.log(k))

    return `${parseFloat((bytes / Math.pow(k, i)).toFixed(dm))} ${sizes[i]}`
}

// Demo code
document.body.innerHTML += `<input type="text" oninput="document.querySelector('p').innerHTML=formatBytes(this.value)" value="1000"><p>1000 Bytes</p>`

Minified version (by StackOverflow’s community, minified by JSCompress)

function formatBytes(a,b=2){if(!+a)return"0 Bytes";const c=0>b?0:b,d=Math.floor(Math.log(a)/Math.log(1024));return`${parseFloat((a/Math.pow(1024,d)).toFixed(c))} ${["Bytes","KB","MB","GB","TB","PB","EB","ZB","YB"][d]}`}

Usage:

// formatBytes(bytes, decimals)

formatBytes(1024)       // 1 KB
formatBytes('1024')     // 1 KB
formatBytes(1234)       // 1.21 KB
formatBytes(1234, 3)    // 1.205 KB
formatBytes(0)          // 0 Bytes
formatBytes('0')        // 0 Bytes

PS : Change k = 1000 or sizes = ["..."] as you want (bits or bytes)

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